I have changed now some settings to reduce connections to gmail. In my opinion I didn´t have so much (labels in outlook, labels in aqua-mail, gsyncit) but it sees that it was enough for Google to throttle all my connections. Right now aqua-mail needs 4 -5 sec to sync. So this is all right now.
I still have the question what the setting "25 per site" means. The rest of the hundred of mails will not be synced?